Editing Photographic developer (section)

==Colour development==
In colour and [[chromogenic]] black-and-white photography, a similar development process is used except that the reduction of silver simultaneously oxidizes the paraphenylene colour developing agent which then takes part in the production of dye-stuffs in the emulsion by reacting with the appropriate couplers. There are three distinct processes used here. The [[C-41 process]] is used for almost all colour negative films and in this process [[dye coupler]]s in the emulsion react with the oxidized [[Color Developing Agent 4|colour developing agent]] in the developer solution to generate the visible dyes. An almost identical process is then used to produce colour prints from films. The developing agents used are derivates of [[paraphenylene diamine]].

In colour negative films,<ref>Photographic Almanac, 1956, pp. 429–423.</ref> there are 3 types of dye couplers. There are the normal cyan, magenta and yellow dye forming couplers, but also there is a magenta coloured cyan masking coupler and a yellow coloured magenta masking coupler. These form respectively normal cyan dye, and magenta dye, but form an orange positive mask to correct colour. In addition, there is a third type of coupler called a DIR (Developer Inhibitor Release) coupler. This coupler releases a powerful inhibitor during dye formation, which affects edge effects and causes effects between layers to enhance overall image quality.